Results 41 to 50 of about 335 (183)
Fine multidegrees, universal Gröbner bases, and matrix Schubert varieties
Abstract We give a criterion for a collection of polynomials to be a universal Gröbner basis for an ideal in terms of the multidegree of the closure of the corresponding affine variety in (P1)N$(\mathbb {P}^1)^N$. This criterion can be used to give simple proofs of several existing results on universal Gröbner bases.
Daoji Huang, Matt Larson
wiley +1 more source
We show that an adjoint of a loopless matroid is connected if and only if it itself is connected. Our first goal is to study the adjoint of modular matroids. We prove that a modular matroid has only one adjoint (up to isomorphism) which can be given by its opposite lattice, and proceed to present some alternative characterizations of modular matroids ...
Houshan Fu, Chunming Tang, Suijie Wang
openaire +2 more sources
How to see the forest despite the trees
Abstract One of the major starting points of discrete optimization is the theorem of Nash‐Williams and Tutte on the existence of k$k$ disjoint spanning trees of a graph, along with its counterpart on the existence of k$k$ forests covering all edges of the graph.
Erika Bérczi‐Kovács, András Frank
wiley +1 more source
Interpolation, box splines, and lattice points in zonotopes [PDF]
Given a finite list of vectors $X \subseteq \mathbb{R}^d$, one can define the box spline $B_X$. Box splines are piecewise polynomial functions that are used in approximation theory. They are also interesting from a combinatorial point of view and many of
Matthias Lenz
doaj +1 more source
Lower bounds for cube‐ideal set‐systems
Abstract A set‐system S⊆{0,1}n$S\subseteq \lbrace 0,1\rbrace ^n$ is cube‐ideal if its convex hull can be described by capacity and generalized set covering inequalities. In this paper, we use combinatorics, convex geometry, and polyhedral theory to give exponential lower bounds on the size of cube‐ideal set‐systems, and linear lower bounds on their ...
Ahmad Abdi +3 more
wiley +1 more source
Secret sharing is an important building block in cryptography. All explicit secret sharing schemes which are known to have optimal complexity are multi-linear, thus are closely related to linear codes.
Csirmaz Laszlo
doaj +1 more source
Bijections for lattice paths between two boundaries [PDF]
We prove that on the set of lattice paths with steps $N=(0,1)$ and $E=(1,0)$ that lie between two boundaries $B$ and $T$, the two statistics `number of $E$ steps shared with $B$' and `number of $E$ steps shared with $T$' have a symmetric joint ...
Sergi Elizalde, Martin Rubey
doaj +1 more source
Skew shapes, Ehrhart positivity, and beyond
Abstract A classical result by Kreweras (1965) allows one to compute the number of plane partitions of a given skew shape and bounded parts as certain determinants. We prove that these determinants expand as polynomials with nonnegative coefficients.
Luis Ferroni +2 more
wiley +1 more source
There are several known results concerning how matroids can be induced from given matroids by a bipartite graph and the properties that are inherited in this way. The purpose of this note is to extend some of these results to the situation where the bipartite graph is replaced by an arbitrary directed graph.
openaire +1 more source
Elementary lift and single element coextension of a binary gammoid
It is known that every binary elementary lift of a binary matroid is a matroid obtained by applying the splitting operation on that matroid. An elementary lift of a binary gammoid need not be a binary gammoid.
Shital Dilip Solanki +2 more
doaj +1 more source

